Since your manifold doesn't have super long runners that would add to the stress, I would say you don't need a brace. People running long tube Top Speed manifolds don't need braces and they're fine. I ran that kind of setup for a couple thousand miles, no probs.
If you want peace of mind, you could have a support welded from the turbo flange to a place that bolts to the head. Really not necessary, though.
Lastly, 10.9 bolts are way overkill. 8.8 bolts would do just fine and even that's stronger than necessary.
1992 Eagle Talon TSi - sold (POS)
2002 Mustang GT - sold
2002 SVTF - sold
2008.5 Mazdaspeed3 GT - cursed
2003 350Z Track - basically stock, and it runs